DE1543845B1 - Process for the purification of synthetically produced amino acids - Google Patents

Description

method has been proposed, however, these 10 and urea derivatives, the crude glycine and acetic acid

up to now for synthetically produced aqueous crude Amino acid solutions containing various inorganic salts and organic intermediates with one Molecular weight on the order of the amino acid has not been satisfactory.

The invention makes a simple and economical one Process for the purification of amino acids and in particular of methionine by electrodialysis made available, with a synthetic Chloroacetic acid and the crude alanine aminopropionitrile and dipropionitrile.

The diaphragms used in the process according to the invention are strongly acidic, cation-exchanging membranes which contain sulfonic acid groups, and strongly basic, anion-exchanging membranes which contain quaternary ammonium groups.
When using electrodialysis with ion exchange

table-made, aqueous, crude amino acid a 20 exchanging membranes for the purification of High purity amino acid is obtained. More amino acids the performance depends on the Aims and advantages of the method according to the invention permselectivity for the amino acids and the tackle from the following description. organic and organic impurities. The invention accordingly relates to a method for permselectivity is dependent on various factors Purification of synthetically produced 25 affected, e.g. B. the pH value, the temperature and Amino acids, which is characterized by the concentration of the solution to be treated, the that an aqueous, crude amino acid solution to a current density and voltage and the water content of the pH membrane corresponding to the isoelectric point.

set and at a temperature of 10 to 30 ⁰ C. The temperature is preferably 15 to 25 ° C.

with a flow rate of 0.2 to 30. The concentration of the solution is adjusted so that

they below a value of about nine tenths of the solubility the amino acid at the pH in question and the temperature concerned, d. H. lower is than the solubility of the amino acid.

a conversion number above 0.90 for sodium ions 35. An aqueous methionine solution which is introduced into the first and a breaking strength above 4 kg / cm ² and strong electrodialysis zone contains e.g. B. about

2 to 7 percent by weight methionine and about 3 to 6 percent by weight inorganic compounds, such as Sodium chloride and ammonium chloride.

In the second electrodialysis zone, the aqueous amino acid solution has the same pH and value same temperature and concentration as in the first electrodialysis zone. At the end point of the

0.3 m ³ / h m ^{2 is introduced} into a first electrodialysis zone in which strongly acidic, cation-exchanging membranes with an effective resistance of at most 14 ohms / cm ² between the anode and cathode,

basic anion-exchanging membranes with an effective resistance of at most 9 ohms / cm ² , a transfer number over 0.92 for chlorine ions and a breaking strength over 4 kg / cm ² are arranged alternately in the same number, with the current density 1 to 5 amps / dm ² is that the aqueous amino acid solution after reaching a specific resistance of 250 to 300 Ω · cm with a flow second cleaning in the second electrodialysis zone

speed from 0.1 to 0.2 m ³ / h - m ² in a second 45, the current density reaches 0.01 to 0.05 amp./dm ² .

Electrodialysis zone is introduced which corresponds to the first zone and in which the current density is 0.01 to 1 Amp./dm ² , and that the solution thus obtained is spray-dried after reaching a resistivity of 2000 to 3000 Ω · em. In this way, highly purified, crystalline amino acids can be obtained.

According to the process according to the invention, organically prepared neutral, acidic and The process according to the invention can be carried out batchwise, semicontinuously or continuously will.

The process according to the invention is explained with reference to the drawing, which continuously shows an embodiment of the invention as a flow diagram. A synthetically produced, aqueous amino acid solution is introduced through a vessel 1 into the first electrodialysis device A , in which the first cleaning

basic amino acids are purified. Examples for 55 takes place,
suitable amino acids to be purified are alanine, the aqueous obtained after the first purification

Arginine, asparagine, aspartic acid, citrulline, cysteine, amino acid solution is circulated into vessel 1 Cystine, diiodotyrosine, glutamic acid, glutamine, glycine, histidine, hydroxylysine, hydroxyglutamic acid,

returned, while part of the solution through a vessel 3 in the second electrodialysis device B is

Hydroxyproline, Isoleucine, Leucine, Lysine, Methionine, 60 leads in which the second purification takes place. The norleucine, ornithine, phenylalanine, proline, serine, fluid consumed from the first electrodialysis-threonine, thyroxine, tryptophan, tyrosine and valine.
The inventive method is preferred

device A is led into the vessel 2 and used as the electrofluid for the electrodialysis devices A and B , then it is cleaned, while

those of methionine, are used. · 65 rend the used liquid as the outlet liquid

Preparative organic method for making the electrodialysis device A is used.

The purified in the second electrodialysis device B aqueous amino acid solution is in the Gs-

for the purification of neutral amino acids, especially

p g g

of amino acids are e.g. B. the Strecker synthesis or the amination of -halocarboxylic acids. the

First cleaning: 6.0 6.0 pH of the feed solution .. 20 ° C 20 ° C Treatment temperature Average flow 0.25 m ³ / h m ² 0.1 m ³ / h m ² speed 2.5 to 0.5 amps / dm ² 0.5 to Current density 0.05 amps / dm ² Specific resistance 200 ohms / cm at the end point at 25 ° C 1500 ohms / cm at 25 ° C Second cleaning: pH of the solution Treatment temperature Average flow speed Current density Specific resistance at the end point

3 4

barrel 3 is returned in the circuit during a yield of 97 ° / _0, based on the methionine

Part of the solution in a spray dryer 6 amino crude aqueous methionine solution.

Acid crystals of high purity can be obtained.

Methionine in this way is z. B. with a pure example2

degree of at least 97% gained. 5 A compound made from monochloroacetic acid and ammonia

The spent liquid from the second electrolyte crude aqueous glycine solution containing 2 weight dialysis machine is passed through a vessel 4 into one percent glycine, 6 weight percent ammonium chloride, barrel 5 for feed recycle, 0.5 weight percent sodium acetate and traces of vinegar during the spent liquid from the vessel 4 acid and monochloroacetic acid. The solution is purified as the discharge liquid of the electrodialysis apparatus B io in the same manner as in Example 1 using and observing the used liquid from the following treatment conditions. Vessel 5 is cleaned. Part of the liquid will
returned to the vessel 1 to increase the yield
Increase Amino Acid.

The following examples explain the process according to the invention.

example 1

One from / J-methyl mercaptopropionaldehyde by 20 Crude aqueous methionine solution obtained by Strecker syntheses has the following composition and composition the following pH value:

Weight percent

Methionine 2.5 ² 5

5-jS-methylcaptoethylhydantoin ... 0.05

5- / S-methyl mercapto ethyl acid 0.2

Methionine sulfoxide 0.02

NaCl 4

NH ₆ Cl lane 3 <>

H ₂ O remainder

pH 5.5 Glycine crystals with one degree of purity are obtained

of 97 percent by weight and in 95% yield,

According to the invention, the above solution is based on the glycine content of the crude aqueous glycine solution shown in the flow chart in the drawing.
cleans. The solution is poured through vessel 1 into Beist) iel3

first electrodialysis out in which the

primary cleaning takes place. The temperature is a crude, aqueous, prepared from aminopropionitrile

30 ° C ₅ the average flow rate alanine solution contains 5 weight percent alanine, speed 0.3 m ³ / h · m ² and the current density between 3 and 4 ° small amounts of aminopropionitrile and diamino-1 amp./dm ² . When the resistivity reaches propionitrile, 8 weight percent sodium chloride, and 300 ohms / cm (25 ° C), the primary purity is 15 weight percent ammonium chloride. The solution is terminated, and the solution is purged through the vessel 3 in the same manner as in Example 1, fed into the second electrodialysis device. In the primary purification stage, where the following treatment conditions are met, about 95% of the Na- 45 are
triumchlorids and the entire ammonium chloride e _tting Reinisuna ·
been removed. As the outlet liquid and electrodes- _TT , J, 1 · '1 r » ct \

liquid becomes an aqueous 1% sodium chloride pH of the feed solution .. 6 0

solution through the ««, Ä electrodialysis- SSSSL ^ * °

device returned. In the second electric 50,. ,. . . ni ziu 2

swirl device, the temperature is 30 ° C, the <J ™ S ^g ? lfA'2 / H 2

pH 5.5, the average flow range * '

speed 0.15m ³ / hm ² and the current density ^ Pezmscher resistance

between 1 and 0.01 Amp./dm ² . The outlet liquid ^{at the end point is 200} ° £ ™ ξ ™

in the electrodialysis device B in the circuit 55 ₇ . _Ώ . .
returned through the vessel 4, while a part of the second no:

the liquid through a vessel 5 in the circuit into the P ^ ^de r solution 6.0

Vessel 1 out and some of the liquid cleaned. Treatment temperature 25 C

will. In electrodialysis devices A and B, average flow

the same electrode fluid is found. 60 speed ^ L · f, λ ,

If the specific resistance of the solution is 1 to 0.05 Amp./dm ²

Reaching 2500 ohms / cm (25 ° C) is the secondary purification Resistance

supply ended, after which the solution was 4 percent by weight ^{at the end point 1700} ° Ψ% ™

Methionine, less than 0.01 percent by weight sodium

chloride and a trace of organic intermediates 65 Alanine crystals with one degree of purity are obtained contains. The solution is in the spray dryer 6 of 95 percent by weight and in 95% yield, leads. Methionine crystals are obtained with a purity based on the alanine content of the crude aqueous degree of 97 weight percent and in an off-alanine solution.

Claims (2)

Patent claims: 1. A process for the purification of synthetically produced amino acids, characterized in that an aqueous, crude amino acid solution is adjusted to a pH value corresponding to the isoelectric point and at a temperature of 10 to 30 ° C with a flow rate of 0.2 to 0 , 3 m ³ / h · m ^{2 is introduced} into a first electrodialysis zone, in which between the anode and cathode strongly acidic, cation-exchanging membranes with an effective resistance of at most 14 ohms / cm ² , a conversion number above 0.90 for sodium ions and a breaking strength Above 4 kg / cm ² and strongly basic andon-exchanging membranes with an effective resistance of at most 9 ohm / cm ² , a transfer rate above 0.92 for chlorine ions and a breaking strength above 4 kg / cm ² are arranged alternately in the same number, with the current density 1 to 5 Amp./dm ² is that the aqueous amino acid solution after reaching a specific resistance of 250 to 300 Ω · cm mi t a flow rate of 0.1 to 0.2 m ³ / h ■ m ^{2 is introduced} into a second electrodialysis zone, which corresponds to the first zone and in which the current density is 0.01 to 1 Amp./dm ² , and that the solution obtained in this way is spray-dried after reaching a specific resistance of 2000 to 3000 Ω · cm. 2. The method according to claim 1, characterized in that methionine is purified. 1 sheet of drawings